Many vinyl-based monomers are prone to spontaneous undesirable polymerization during manufacturing and purification, as well as during handling, transportation, and storage. For example, the vinyl-based monomers can react under the heat used in manufacturing and purification to undesirably form highly crosslinked polymers. These polymers may form foamy or crusty granules that ultimately plug production lines and equipment, and thereby may potentially cause physical damage.
Nitroxide-based compounds can inhibit the undesirable polymerization of vinyl-based monomers. In particular, nitroxide-based compounds can be fast-acting inhibitors, and can be used alone or in combination with slower-acting polymerization retarders or antioxidants. To minimize the undesirable polymerization of the vinyl-based monomers, an optimized dosage of nitroxide-based inhibitors may need to be continuously provided into the liquid phase of the vinyl-based monomers during manufacturing and purification. There thus exists an ongoing need to develop systems and methods of monitoring a residual concentration of the nitroxide-based inhibitors substantially in real time at any given point in time so as to immediately provide an optimized dosage of the nitroxide-based inhibitor during a manufacturing process without interruption.